See this node for more information about use and require. If you want a Tk-able script to run even when Tk is not installed you need to go with require. But this is not without some hassles, as noted in the referenced node.

In reply to (ichi) Re: use/require TK, What up with that?? by ichimunki
in thread use/require TK, What up with that?? by byoungvt

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